Extraction and complex formation of niobium(V) with 3-hydroxy-2-methyl-1-(4-tolyl)-4-pyridone

The extraction of niobium(V) from aqueous hydrochloric and sulphuric acid solutions with 3-hydroxy-2-methyl-1-(4-tolyl)-4-pyridone (HY) dissolved in chloroform is described. Niobium(V) can be quantitatively extracted with HY in the form of two different complexes depending on the chloride ion concentration in the aqueous phase. At a low chloride concentration or without chloride in the aqueous phase niobium(V) is extracted with HY in the form of Nb(OH)₃Y₂ and at a high chloride concentration as a mixed Nb(OH)₃ClY complex. Niobium extraction with HY enables the separation of niobium(V) from zirconium(IV) and hafnium(IV). The formation of a mixed chloro-4-pyridone complex is also applicable for the spectrophotometric determination of niobium in the organic phase at the maximum absorption at 350 nm.     

Formation and Extraction of Niobium(V) Complex with Xylenol Orange in the Presence of a 4-Pyridone Derivative

Xylenol orange (XO) is a suitable reagent for the spectrophotometric determination of niobium in a weakly acidic medium. The present study shows that the addition of 3-hydroxy-2-methyl-1-phenyl-4-pyridone (HX) influences the complex formation as well as the spectroscopic properties of this colored system. To prevent formation of niobium(V) hydrolyzed species in water, tartaric acid was used when preparing the niobium stock solution. The red-violet colored complex formed by heating niobium(V) with xylenol orange (XO) in the presence of HX at pH=3 has a maximum absorption wavelength at 565 nm. The complex can be extracted by a chloroform solution of tetraphenylphosphonium (TPP) chloride. The optimum reaction conditions and other parameters for complex formation have been evaluated. The mechanism of extraction is probably based on the formation of the associated ion pair between the tetraphenylphosphonium cation and the mixed Nb(V)-XO-HX anion. The extracted complex in chloroform showed a maximum absorbance at 585 nm with the corresponding molar absorption coefficient being 3.72×10⁴ L⋅mol⁻¹⋅cm⁻¹, and obeys Beer’s law in the range 3×10⁻⁶ to 3×10⁻⁵ mol⋅L⁻¹.     

Spectrofluorimetric determination of iridium(IV) traces using 4-pyridone derivatives

A new spectrofluorimetric determination of iridium(IV) with 3-hydroxy-2-methyl-1-phenyl-4-pyridone (HX) or 3-hydroxy-2-methyl-1-(4-tolyl)-4-pyridone (HY) is reported. Iridium(IV) react with HX or HY and chelates were extracted into chloroform or dichloromethane. The organic phase showed fluorescence. The fluorescence measurements to quantify iridium were carried out in its fluorescent band centred at λ_ex=373 nm and λ_em=480 nm. Under optimal conditions, the calibration graphs were linear over the concentration range of 0.1-7.6 μg ml⁻¹ of iridium for Ir(IV)-HX and 0.1-5.8 μg ml⁻¹ for Ir(IV)-HY with a correlation coefficients of 0.999 and 0.992 and relative standard deviation of ±1.1%.The method is free from interference by Rh(III) and Pt(IV), which normally interfere with other methods. Iridium can be determined in the presence of 300-fold excess of rhodium(III) and 10-fold excess of platinum(IV).The method was applied successfully to the determination of iridium in some synthetic mixtures and mineral sample gave satisfactory results.     

Extraction and spectrophotometric determination of titanium(iv) with 3-hydroxy-2-methyl-1-(4-tolyl)-4-pyridone

Titanium(IV) in sulphuric, perchloric and hydrochloric acid media reacts with 3-hydroxy-2-methyl-1-(4-tolyl)-4-pyridone (HY) to give a complex which is extractable into chloroform. The composition of the extractable complex depends on the acidity of the aqueous phase and on which mineral acid is used. The mixed titanium-perchlorate-HY complex which is formed in the presence of excess of perchlorate is the most suitable for the spectrophotometric determination of titanium. The molar absorptivity of the complex is 1.6×10⁴1·mole^–1·cm^–1 at 355 nm. The optimum titanium concentration range is 0.5–6,g/ml. The method has been successfully applied to the determination of titanium in samples of bauxite and alumina refractory.     

Spectrophotometric determination of tungsten as a mixed thiocyanate-1-phenyl-2-methyl-3-hydroxy-4-pyridone complex

Spectrophotometric determination of tungsten with thiocyanate was described. Tungsten(VI) was reduced with tin(II) chloride in hydrochloric acid solution, complexed with thiocyanate ions, and the complex formed was extracted with 1-phenyl-2-methyl-3-hydroxy-4-pyridone (HX) in chloroform. The extracted complex had the ratio W:SCN:HX 1:3:2. The method described is sensitive, selective, and reproducible. The color of the tungsten-thiocyanate complex in the organic phase is stable. Few metals interfere; the separation of the interfering elements was discussed.     

Mixed Ligand Complexes of Vanadium(V): Extraction With Some New Hydroxamic Acids and Application in Steel.,Rock and Environmental Anaysis

Abstract

Five new substitued hydroxamic acids are used for extraction and spectrophotometric determination of vanadium(V) in trace amounts. the binary complex of vanadium (V) with H-p-ciloropheny 1-3,4,5-trimethoxycinnamohdroxamic acid (PTCHA) and the mixed ligand complex of vanadium (V) with N-p-cinlorpheny-p-chlorophenoxyisobutyrohydroxamic acid (PP3HA) and thiocyanete were studied. The molar absorbtivities of the bluish violet vanadium(V) hydroxamate and mixed ligand complexes are 6.9 × 10³ and 1.1 × 10⁴ cm³ mol^?3 cm^?1, respectively. The vanadium is also determined with AAs and the method is applied for its determination in steel. alloy, rock and environmental samples.     

Extractive spectrophotometric determination of molybdenum as a thiocyanate-2-acetylpyridinethiosemicarbazone complex

A new spectrophotometric method for the determination of molybdenum is based on the extraction of the orange red molybdenum thiocyanate-2-acetylpyridinethiosemicarbazone complex into chloroform from hydrochloric acid. The complex has an absorption maximum at 470 nm with a molar absorptivity of 1.7 × 10⁴ liters mol^?1 cm^?1. Beer's law is valid from 0.1 to 6.5 ppm of molybdenum. The equilibrium shift method indicated a 1:4:2 complex. The method has been used successfully for the determination of molybdenum in molybdenum steels.     

N-p-tolyl-2-furohydroxamic Acid as the Extracting and Spectrophotometric Reagent for Vanadium(V)

Abstract

A simple and rapid spectrophotometric determination of vanadium(V) is described. The vanadium-N-p-tolyl-2-furohydroxamic acid complex is extracted into chloroform form 6–8 molar hydrochloric acid solution. Maximum absorbance occurs at 540 nm and Beer's Law is obeyed over the range of 0–15 μg of vanadium in the organic phase. The molar absorptivity is 3.0 × 10³ mole^?1 cm^?1 at 540 nm.

Vanadium could be determined in high purity niobium and tantalum metals, cast iron, steel, non ferrous alloys and silicates. Vanadium could be determined in the presence of several commonly occurring cations.     

Extraction and separation of uranium(VI) and protactinium(V) with 1-(4-tolyl)-2-methyl-3-hydroxy-4-pyridone

Summary The extraction of uranium(VI) from aqueous hydrochloric or nitric acid, and the extraction of protactinium from hydrochloric acid by 1-(4-tolyl)-2-methyl-3-hydroxy-4-pyridone (HY) dissolved in chloroform has been studied. At pH >4, uranium (VI) is quantitatively extracted while at pH < 1 practically all the uranium remains in the aqueous phase. At hydrochloric acid concentrations lower than 1M, protactinium(V) is quantitatively extracted while at hydrochloric acid concentration higher than 5M practically all the protactinium remains in the aqueous phase. This difference in extraction of uranium and protactinium was utilized for their separation. From 0.5M hydrochloric acid, protactinium is quantitatively extracted, and separated from uranium.The composition of the extracted uranium(VI) and protactinium (V) complexes was studied. A uranium complex with the formula UO₂Y₂ · HY was isolated from the chloroform solution. The solution of this complex in chloroform has a maximum absorbance at 319 nm and the molar absorptivity is 3.1×10⁴ l · mole^–1 · cm^–1. Owing to this property uranium can be determined spectro-photometrically directly in the organic phase.

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Zusammenfassung Die Extraktion von Uran(VI) aus wäßriger Salzsäure oder Salpetersäure sowie die Extraktion von Protaktinium aus Salzsäure mit 1-(4-Tolyl)-2-methyl-3-hydroxy-4-pyridon (HY) in chloroformischer Lösung wurde untersucht. Bei pH > 4 wird U(VI) quantitativ extrahiert, während bei pH < 1 praktisch alles Uran in der wäßrigen Phase bleibt. Bei Salzsäurekonzen-trationen unter 1-m wird Protaktinium (V) quantitativ extrahiert, während bei Salzsäurekonzentrationen über 5-m praktisch alles Pa in der wäßrigen Phase bleibt. Dieser Unterschied bei der Extraktion der beiden Elemente wurde für deren Trennung benützt. Pa wird aus 0,5-m Salzsäure quantitativ extrahiert und so von Uran getrennt.Die Zusammensetzung der extrahierten U (VI)- und Pa (V)-Komplexe wurde untersucht. Ein Urankomplex der Formel UO₂ · Y₂ · HY wurde aus der Chloroformlösung isoliert. Die Lösung dieses Komplexes in Chloroform hat ein Absorptionsmaximum bei 319 nm und eine molare Extinktion von 3,1 · 10⁴ l · mol^–1 · cm^–1. Auf Grund dieser Eigenschaft kann Uran spektrophotometrisch direkt in der organischen Phase bestimmt werden.

     

Determination of Vanadium with Chlorosubstituted Hydroxamic Acids for Photometric and Atomic Absorption Spectrophotometric Determination

Abstract

The eight newly synthesized chlorosubstituted hydroxamic acids are described for the extraction and spectrophotometric determination of vanadium. The sensitive and selective reagent, N-m-Chlorophenylpalmito hydroxamic acid, (m-CPPHA), which gives violet coloured vanadium complex was extracted with chloroform from 6M HCl. The violet coloured complex thus obtained has a maximum absorbance at 520 nm and molar absorptivity 4.9 ± 10³1mol^?1cm^?1. The Beer's law obeyed in the region 0.50-12.0ppm. Effects of acidity, reagent concentration, diverse ions have also been investigated. A comparison has been made with atomic absorption spectrophotometric method. Vanadium has been determined in the environment, e.g. plant, soil, rock, etc.     

Solvent Extraction of Vanadium(V) as a Ternary Complex with N-Hydroxy-N-p-Chlorophenyl-N′-(2-Methyl-5-Chloro)-Phenyl-p-Toluamidine Hydrochloride and p-Chlorophenol

N-Hydroxy-N-p-chlorophenyl-N′-(2-methyl-5-chloro)-phenyl-p-toluamidine hydrochloride (HCPMCPTH) reacts with vanadium(V) to form a 1:2 (metal:reagent) blue-violet complex which can be quantitatively extracted into chloroform from acetic acid solutions. The deep blue adduct having 1:2:1 (V:HCPMCPTH:PCP) stoichiometry gets quantitatively extracted into chloroform from 0–2.5 M acetic acid media. The formation of the ternary complex has been made the basis for the development of a simple, rapid, sensitive and selective extractive-photometric method for the determination of microamounts of vanadium(V). The method has been applied to the determination of vanadium in steels.     

Extractive Determination of Vanadium in Fungi Samples

A new reagent system has been reported for the extractive separation and simultaneous spectrophotometric de termination of vanadium (V). The method is based on the formation of a water in soluble blue‐violet V(V) complex with N‐hydroxy‐N‐m‐tolyl‐N′‐phenylbenzamidine (HTPBA), and neutral surfactant Triton X‐100 into chloroform over an acidity range of 1.0–10.0 M acetic acid. The complex shows a broad absorption maximum at 570 nm, when measured against a chloroform blank. The λ_max (570 nm) of the complex and that of re agent (313 nm) are well separated, hence the excess of the reagent does not interfere in the spectrophotometric de termination of the metal. The molar absorptivity (?) of the complex is (4.74) × 10³ 1 mol^?1 cm^?1. The linearity of the calibration curve is followed between 0.5–12.0 μg mL^?1 with slope, intercept and correlation coefficient of 9.16× 10^?2, 4.5 × 10^?3 and 0.999, respectively. The detection limit of the method is 45 μgl^?1. The proposed re agent system provides significantly higher tolerance limit for iron (500 μg mL^?1) and also various metalions commonly associated with vanadium did not interfere. The method was applied for the deter mi nation of vanadium content of three samples i.e. Spirogyra, Puccinia and Riccia.     

Extraction Spectrophotometric Determination of Vanadium in Industrial Waste Water

A new and simple extraction spectrophotometric method for the determination of vanadium(V) with KIO₄, N‐phenylbenzohydroxamic acid (PBHA) and crystal violet (CV), in industrial waste water samples is described. It is based on the extraction of mixed‐ligand complex V(V)‐IO₄^? ‐PBHA‐CV⁺ into chloroform solution over 2‐7 MHC1. The molar absorptivity of the complex is (7.20) × 10³1 mol^?1 cm^?1 at λ_max 535 nm. The detection limit of the method is 44 μg 1^?1 V. The linearity of the calibration curve is followed up to 6 μgmL^?1 in the organic solution with slope, intercept and correlation coefficient of 1.34 × 10^?1, 6.7 × 10^?3 and +0.99, respectively. This method enhances the sensitivity of the conventional PBHA method for the determination of vanadium, and is free from interferences of other metal ions commonly associated with vanadium. The method has been successfully tested for the determination of V in the industrial waste water samples.     

Extractive Spectrqphotometric Determination of Vanadium Liith o-Aminobenzo-Hydroxamic Acid

Abstract

A new spectrophotometric method for vanadium determination is proposed. The method is based on the extraction in Adogen-toluene solution of the complex formed between V(V) and o-Aminobenzohydraxámic acid

The method allows determination of 50 to 110 μg of V(V). The error and the apparent molar absorptivity are 1.2% and 5.2 ± 10³ l.mol^?1. cm^?1 respectively. The interferences caused by foreign ions have been established. The method is applied with success to determination of vanadium in petroleum crudes.     

Selective spectrophotometric determination of vanadium in silicates with a new pyridylazophenol in the presence of hydrogen peroxide

The synthesis of a new heterocyclic azo compound, 2-(3,5-dibromo-4-methyl-2-pyridylazo)-5-diethylaminophcnol (3,5-Br-MEPADAP is described. The dye forms an intensely coloured (ε=4.11·10⁴ 1 mole^-1 cm^-1 at 615 nm) unstable chelate with vanadium(V) in weakly acidic medium. However, vanadium(V) reacts with 3,5-Br-MEPADAP and hydrogen peroxide in 0.5 M sulphuric acid to form a stable 1:1:1 ternary complex which is extractable in several solvents. In the presence of fluoride, the reaction is highly selective for vanadium(V); only large amounts of halides, oxidizing and reducing agents interfere. The effective molar absorptivity is 5.43 ·10⁴ 1 mole^-1 cm^-1 at 615 nm in chloroform. The reagent system was applied for the direct spectrophotometric determination of vanadium in a wide range of silicates; the average relative standard deviation was 0.45 %. The accuracy of the vanadium values obtained for ten international standard rocks compares well with the currently accepted most probable values.     

Spectrophotometric determination of titanium as tetraphenylarsonium or tetraphenylphosphonium thiocyanato-titanate

The spectrophotometric determination of titanium(IV) with thiocyanate by extraction of the tetraphenylarsonium and tetraphenylphosphonium ion-association complexes is described. The extracted complexes in chloroform have a maximum absorbance at 420 nm, obey Beer's law in the range 0.1–1 μg Ti ml^?1, and are stable for at least 5 hr. The molar absorptivity of the method is 7.5 × 10⁴ liters mol^?1 cm^?1. The described method is sensitive, selective, and reproducible. The composition of the extracted complexes was studied in solution and in solid state. The complexes [(C₆H₅)₄X]₂ [Ti(NCS)₆] (X = As, P) were isolated from the chloroform solution.     

Spectrophotometric Determination of Vanadium in Complex Materials Using N-m-TMBHA and Thiocyanate

Abstract

Vanadium(V) reacts with N-m-Tolyl-p-methoxy benzohydroxamic acid to form 1:2 (metal to ligand) complex containing a basic V=O group and an acidic V-OH group, which forms addition compounds with thiocyanate to give a hyper and bathochromic effect in chloroform. On the basis of this bathochromic effect of thiocyanate a rapid, selective and sensitive method for the spectrophotometric determination of vanadium(V) has been developed. The blue coloured complex of vanadium(V) is extractable in chloroform having absorption maxima at 580nm and max 7100 ±50 1. mole^?1 cm^?1. The method is free from interferences of Mo(VI), W(VI), Zr(IV) and has been successfully applied for the analysis of steels and other complex materials.     

Extraction—Spectrophotometric determination of nickel with 2-hydroxy-1-naphthaldoxime

A method for the solvent extraction—spectrophotometric determination of nickel with 2-hydroxyl-1-naphthaldoxime (HNA) has been studied. The method is based upon the formation of a nickel—HNA complex which is extracted into chloroform from an aqueous solution of pH 5.8. The nickel—HNA complex in chloroform exhibits an absorption maximum at 410 nm with molar absorptivity of 8.1 × 10³ liters mol^?1 cm^?1. Beer's law is applicable in the range from 5 to 50 μg of nickel. The mole ratio of the complex and effect of interfering ions are described.     

Liquid-liquid extraction and cloud point extraction for spectrophotometric determination of vanadium using 4-(2-pyridylazo)resorcinol

Liquid-liquid extraction (LLE) and cloud point extraction (CPE) of vanadium(V) ternary complexes with 4-(2-pyridylazo)resorcinol (PAR) and 2,3,5-triphenyl-2H-tetrazolum chloride (TTC) were investigated. The optimal conditions for vanadium extraction and spectrophotometric determination were identified. The composition (V: PAR: TTC) of the extracted species was 1:2:3 (optimal conditions; LLE), 2:2:2 (low reagents concentrations; LLE), 1:1:1 (short heating time;CPE), and 1: 1: 1 + 1: 1: 0 (optimal extraction conditions; CPE). LLE, performed in the presence of 1,2-diaminocyclohexane-N,N,N′,N′-tetraacetic acid and NH₄F as masking agents, afforded the sensitive, selective, precise, and inexpensive spectrophotometric determination of vanadium. The absorption maximum, molar absorptivity, limit of detection, and linear working range were 559 nm, 1.95 × 10⁵ dm³ mol^?1 cm^?1,0.7 ng cm^?3, and 2.2–510 ng cm^?3, respectively. The procedure thus developed was applied to the analysis of drinking waters and steels. The relative standard deviations for V(V) determination were below 9.4 % (4–6 × 10^?7 mass %; water samples) and 2.12 % (1–3 mass %; steel samples).     

The spectrophotometry and solvent-extraction behaviour of iron(III), vanadium(IV and V) and titanium(IV) chelates of 1-(o-carboxyphenyl)-3-hydroxy-3-methyltriazene

l-(o-Carboxyphenyl)-3-hydroxy-3-methyltriazene is proposed as an excellent reagent for the spectrophotometric determination of iron(III) and titanium(IV), and also for the separation of titanium from a large quantity of iron as well as other cations and anions. Iron(III) forms an anionic violet 1:2 complex at pH 4.0–9.4, and a cationic green 1:1 complex at pH 1.5–2.0, with absorption maxima at 570 nm and 660 nm, respectively. The violet complex is quantitatively extracted in chloroform containing n-octylamine at pH 3.0–9.0. The green and the violet iron(III) complexes obey Beer's law, the respective optimal ranges being 8.9–35.8 and 3.9–11.2 p.p.m. The yellow titanium chelate extracted into chloroform (absorption maximum at 410 nm) between pH 1.0 and 3.5, can be re-extracted into concentrated sulphuric acid a violet colour being produced with absorption maximum at 530 nm. Beer's law is obeyed in the ranges 0.8–5.7 p.p.m. for the titanium complex in chloroform and 3.4–19.2 p.p.m. when extracted in concentrated sulphuric acid. Interferences from diverse ions are not severe. Procedures for the separation and determination of titanium in the presence of a large quantity of iron are given. The isolation of the iron(III) and vanadium(IV and V) complexes, and their properties, are described.